1. Field of the Invention
The present invention relates to a stator core and more specifically, to a stator core that is suitable for high-speed rotation and a motor including such a stator.
2. Description of the Related Art
A three-slot stator core is known to be a stator core that is suitable for high-speed rotation. A one-piece type stator core 100 as shown in FIG. 9 is generally used as the stator core mentioned above. Referring to FIG. 9, the stator core 100 includes a core-back portion 101 and teeth portions 102. Coils are provided in the respective teeth portions 102. Slots 103 for accommodating the coils are formed between the adjoining teeth portions 102.
As shown in FIG. 10, the coils are formed by winding a conductive wire 105 on the teeth portions 102 through insulators 104. A dedicated winding machine is used in winding the conductive wire 105. The winding machine is provided with a nozzle 106 for feeding the conductive wire 105 from a tip end thereof. The nozzle 106 revolves around each of the teeth portions 102 along a specified orbit, whereby the conductive wire 105 is wound on each of the teeth portions 102. A pair of wire ends drawn out from each of the coils is connected to specific terminals. Each of the coils is electrically connected to an external power source or the like through the terminals.
As an example of a conventional high-speed motor, Japanese Utility Model Application Publication No. S50-64905 (JP50-64905A (Utility Model)) discloses a six-slot motor core (stator core) in which a magnetic-pole end surface of a coil groove is substantially perpendicular to the other surface extending from the magnetic-pole end surface.
Japanese Patent Application Publication No. H8-111968 (JP8-111968A) discloses another conventional motor having a six-slot stator core in which the side of a slot facing a core back is provided perpendicularly to the side facing the teeth of the stator core. An one example thereof, there is illustrated a stator core having the same number of sides as the number of teeth and having an external form with a polygonal cross section.